Iranian opposition website Kaleme has published testimony, reported to be signed by 41 prisoners at Iran's Evin prison's infamous ward 350 saying they saw blogger Sattar Beheshti after he had been tortured at the police station. Beheshti died while in custody of Iranian officials.

The report quotes eyewitnesses saying Beheshti told them he had been severely beaten, hanged by his wrists from the ceiling, pushed to the ground and kicked in the head, and also repeatedly threatened to be killed. Eyewitnesses added that his head was swollen, parts of his body bruised and effects of hanging were apparent on his wrists.

On Friday, the U.S. State Department demanded Iranian authorities investigate the apparent murder of Sattar Beheshti, an Iranian blogger who died while in custody earlier this week.

"We are appalled by reports that Iranian authorities tortured and killed blogger and activist Sattar Beheshti during a prison interrogation," said State Department spokesman Victoria Nuland in a statement released Friday. "Besheshti had been arrested for a crime no greater than expressing his political opinion online."

France and Britain are calling on Iran to explain the death in detention of an anti-government blogger who opposition activists say had been tortured.

"We join the international community in demanding the Iranian government investigate this murder, hold accountable those responsible for Beheshti's arrest, torture, and killing, and immediately cease all reported harassment of Beheshti’s family," the U.S. statement read, adding that Beheshti is "just one of thousands of victims of the Iranian government's campaign of violent repression and efforts to curtail basic freedoms at all costs."

Activists say Sattar Beheshti, 35, was arrested in his home in late October, and that his family was asked on Wednesday to pick up his body from a detention center in Tehran.

In his last posting before being arrested, Beheshti wrote that security services had threatened him -- saying his mother "would soon be wearing black" if he continued speaking out.

Officials in France and Britain said they were shocked by reports of Beheshti's death. The British Foreign Office said it appeared to be another attempt to crush any form of free expression in Iran.

Hadi Ghaemi, a spokesman for the International Campaign for Human Rights in Iran said cases like Beheshti's are not uncommon.

"Our organization has documented at least 17 deaths of political prisoners inside Iranian prisons since 2003," he said. "There is no doubt Beheshti was taken to custody, died within less than a week, and his body is already buried without allowing family to have access to it or have an autopsy performed."

He added that the facts of the case were irrefutable and that if the death had been due to natural causes, Iranian authorities could have easily proven it by allowing an autopsy.

Human rights groups Amnesty International and Reporters Without Borders are also calling on Iran to release details of his death.

Iranian officials have not commented on his detention or cause of death. Beheshti's sister, Fatima, told Voice of America's Persian News Network that her brother did not have any history of illnesses.

Mansour Haghighatpour, a member of parliament and deputy head of the national security commission told the Iranian Labour News Agency (ILNA) that there was no need for his commission to get involved and that he is certain that those responsible will address the matter.

A lawyer in Tehran told VOA he had no doubts about what happened to Beheshti.

"Beheshti was under the custody of the cyber police (FATA), and since he was not a famous person, they probably mistreated him with no of fear punishment," he said. "And once it got really bad, they transferred him to the prison to avoid any responsibility. I think this is similar to the story of Zahra Kazemi."

Kazemi, a Canadian-Iranian photographer, was arrested in Iran in 2003 and later died while in custody.The case was widely reported around the world.

Another Iranian, who lives in a city outside of Tehran, told VOA he had doubts about the reports of Beheshti's death and did not have a good feeling about how it all has unravelled.

An Iranian journalist, writing on Facebook said that Ahmadi Moghaddam, head of police and the head of FATA (cyber police), "do not deserve their positions. They must be removed so that the root of these atrocities are removed."

The journalist later told VOA that when these cases happen, the regime stands behind those responsible instead of condemning them and that this "makes the Iranian people believe they approve of these atrocities."